Subject: Re: DEV_B_SIZE
To: Nathan Hawkins <>
From: Terry Lambert <>
List: tech-kern
Date: 01/31/2003 17:10:46
Nathan Hawkins wrote:
> You might want to talk with Veritas. I'm pretty sure their Volume
> Manager's log subdisks assume 512-byte sectors.

Yes, this is true.  It would cause a problem for VXFS, at least
the VXFS whose source code I disked around with for USL's use on
UnixWare; almost all the directory entry management code is
verbatim from the USL UFS sources.

I know that AIX *would not* have a problem on the old HPFS, but the
OS/2 HPFS might have a problem.  I think Solaris, and anyone else
using a UFS derived FS would probably have a problem with directory
entry management, and for those areas I've already noted.  I don't
know if the NXFS I wrote for Novell's NetWare for UNIX product is
still in use anywhere, or not, these days, but if it is, the it
would have a problem, too, both in directory ops, and in secondary
inode management for EA's and resource forks.

The SGI XFS people, Novell, and the GFS people would also be good
ones to ask for input.  Microsoft and Apple, too, if it weren't
obvious.  8-).

> More generally, what impact would this have on existing RAID
> implementations, hardware or software? This is a potentially more
> damaging impact than filesystem semantics.

The real question is sector sparing, when it comes to that, and
whether it's on 4K boundaries or not, etc..  For the most part,
RAID that does parity should not care, but RAID 0 and 1 may be
a problem during a power failure, unless PHK's issue about the
write caching, and the inability to disconnect the bus on the
data portion of the write, is fixed.

-- Terry